The score was arranged and produced by Paul Campbell and the Ulster Orchestra's 50-strong performance was filmed in the Ulster Hall earlier this month.

The high-production video – made by Ulster Rugby's media partner Little Giant Films – also includes cameo appearances from the Civil Service mini rugby team, opera singer Richard Shaffrey and last year's Voice UK winner Andrea Begley, as well as random rugby fans, who join in the singing.

Footage of Ulster's countryside, from Malin Head in Donegal to the Giant's Causeway, provide the backdrop to the promotional film, while rugby legend Willie John McBride wraps it up with the stirring words: "Just remember, when you play Ulster at Ravenhill you are not only playing the 15 players on the field, you are playing the whole province of Ulster."

The film was posted on YouTube and was retweeted almost 400 times on Twitter with an accompanying message repeating McBride's fighting words.

But to the dismay of fans of the White Knights, Saracens responded with a spoof version of the film, with the chant changed to "Stand up for the Saracens".

McBride's words of support were also switched to: "Just remember, when you play Ulster at Ravenhill you are not playing the whole province, you're only playing 15 players, so you are."

The mocking video was posted on the London team's official website, prompting fans to take to Twitter to voice their anger.

Stand up for the Ulstermen performed by The Ulster Orchestra

)

One rugby fan said: "I have just unfollowed @Saracens. They already know why."

Another said: "Someone at Saracens should get sacked for this. Disrespectful."

A third tweeted: "Wow. Stay classy. Saracens."

However, the company behind the Ulster Rugby film said the Saracens parody had backfired and had lost them support in some quarters.

The man who directed the promotional video, Robin Morgan, said he was angry when he first saw the doctored version.

"I thought it was in very poor taste," he said. "To dub over Willie John McBride's words is sacrilege really. But a negative has turned into a positive now.

"Saracens' PR stunt has spectacularly backfired."

The Saracens parody has now been removed from YouTube but an official Stand Up for The Saracens video by Right Said Fred, uploaded four years ago, is still available.